PURPOSE: To recover powdery ore stuck to a cyclone without stopping the operation of a pre-reduction furnace under excellent collecting efficiency by setting plural sets of equipments composed of the cyclone and circulation passage for powdery ore collected with the cyclone in a fluidized bed system powdery oxide ore pre-reduction furnace and using them while alternately changing over.
CONSTITUTION: The powdery oxide ore 2 is supplied into a riser 1 and high temp. reducing gas 3 generated from a smelting reduction furnace at the next process is blown from the bottom part thereof to form the fluidized bed 4 for powdery ore and the pre-reduction is executed. In the riser 1, plural cyclones 6, 6a are parallelly arranged, and after separating exhaust gas 5 accompanied with the powdery ore from the riser with the cyclones, the gas is exhausted from exhaust holes 7, 7a. The powdery ore collected in the cyclones 6, 6a is returned to the fluidized bed 4 through a circulation system 8, 8a and a part thereof is discharged from discharging holes 9, 9a as the pre-reduced powdery ore. In this operation, the process from the riser → cyclone → circulation passage → riser is alternately opened/ closed and by blowing cooling gas from inlet 5, the powdery ore stuck to inner wall of the cyclone is detached and removed, and while executing recovery of the powdery ore with the cyclone, the pre-reducing reaction with the riser is continuously operated.
ITAYA HIROSHI
MOMOKAWA HIDEYUKI
SATO KAZUHIKO
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